FLASH CHROMATOGRAPHY: AREA & APPLICATIONS

 

Table No.1 :-THE PROPERTIES OF COMMONLY USED FLASH SOLVENTS[2]

Solvent

Density (g/ml)

Elution Strength

Solvent Group

Boiling Point (°C)

UV Cut-off (nm)

TLV (ppm)

n-Hexane

0.66

0.01

1

69

195

100

2 2 4-Trimethylpentane

0.69

0.02

1

99

210

300

Cyclohexane

0.77

0.03

1

81

200

100

1 1 2-Trichloromethane

1.48

0.31

8

61

245

50

Toluene

0.87

0.22

7

110

285

100

Dichloromethane

1.33

0.30

5

40

232

100

Ethyl Acetate

0.90

0.45

6

77

256

400

Methyl-t-butyl ether

0.74

0.48

2

55

210

40

Acetone

0.79

0.53

6

56

330

750

Tetrahydrofuran

0.89

0.35

4

66

212

200

Acetonitrile

0.78

0.50

6

82

190

40

Isopropanol

0.79

0.60

3

82

205

400

Ethanol

0.79

0.88

3

78

210

1000

Methanol

0.79

0.70

3

65

205

200

Water

1.00

0.073

8

100

180

-

Column Selection
Select a column that is 10, 20, 40 mm ID based upon preparative requirements. Indeed, Professor Still et al offered this selection given in table below. Single Step Flash Columns (patented) represent an innovative step forward in chromatography. Flash Chromatography is a quick and inexpensive technique for the purification of organic compounds. Thomson flash columns come in a wide variety of sizes ranging from 4g to 300g silica-based for easy scalability of synthetic reactions. Thomson also offers other packing material like Amine and C18 flash columns which enable the end-user to utilize these flash columns for a broad range of reactions.[6]

Table no.2 :-TYPICAL VOLUME OF ELUANT REQUIRED FOR PACKING AND ELUTION [2]

Column Diameter (mm)

Volume of eluent* (ml)

Sample Load (mg)

Rf> 0.2 Rf>0.1

Fraction Size (ml)

10

100

100

40

5

20

200

400

160

10

30

400

900

360

20

40

600

1600

600

30

50

1000

2500

1000

50

* Typical Volume required for equilibrium of the column and elution.

Typical Data of Silica gel Column Grade Adsorbents.[7]
Content : <0.02%
Chloride Content : <0.10%
Loss on Drying: <3%
pH(10% suspension) : 7±0.5
Surface Area : 400–600 m2/gm.

Instrumentation of Flash Chromatography[9][10]

Flash chromatography General consist of following parts
1. Pump Systems.
a) Pump Controller.
b) Vacuum Pump/peristaltic Pump.
2. Sample Injection Systems.
3. Glass Columns, Filling Sets & Column Valves.
4. Precolumns.
5. Fraction Collector.
6. Detectors and Chart Recorders.
7. Computerize LCD Display.

Pump Systems:

Pump Controller
A pressure range up to either 10 bar or 50 bar gives optimum separation results for a broad range of applications. The pump modules can be controlled by three different units. The Pump Controller C610 (for isocratic separation up to 10 bar), the Pump Manager C615 (for isocratic and gradient separation up to 50 bar) and the Control Unit C620.

Pump Controller C-610
The Pump Controller C-610 for one Pump Module C-601 is designed for isocratic separations. The flow rate can be easily adjusted by turning a knob and is indicated by a large illuminated LCD-display. Delivered with a overpressure sensor for maximum safety.

Pump Manager C-615
The Pump Manager C-615 is designed for both isocratic and gradient separations. Fast operation, easy programming and a large graphical display allows a quick and easy set up. Running time, solvent consumption and actual pressure are shown during a separation for maximum optimization. The unit has Input/Outputs for 2 solvent valves and level sensors and includes a pressure sensor and mixing chamber.

Control Unit C-620
The Control Unit C-620 in combination with Sepacore Control provides precise control of the   chromatography system. The following components can be connected to the Control Unit C-620: 2 to 4 Pump Modules C-601 or C-605 Up to 2 Fraction Collectors Up to 8 Detectors e. g. UV, RISequential Modules C-623 or C-625 for automatic sequential chromatography on up to 5 columns or cartridges The Control Unit C-620 is included in the Sepacore Control package

Type of pump

Pump Module C-601, 10 bar
The Pump Controller C-610 with a Pump Module C-601 is used for fast isocratic Flash separations. No programming is needed. The system can be run by two buttons and one knob. Pump Module C-601, 10 bar Silent operating 3-piston Pump Module C-601 for flash chromatography. The pump module provides a constant, pulse-free flow from 2.5 to 250 ml/min and ensures reproducible, fast separation at a maximum working pressure of 10 bar/145 psi. For sample sizes of up to 5 g, pre-packed PP cartridges can be used for the quick, safe implementation of normal phase and reversed phase applications.

Pump Module C-605, 50 bar
The Pump Manager C-615 with a Pump Module C-601/C-605 is used for isocratic Flash separations. This combination allows exploration into the features of the Pump Manager C-615 for solvent selection, timed runs and solvent level control. Pump Module C-605, 50 bar Similar to the Pump Module C-601 but with a maximum working pressure of 50 bar/725 psi. Using the Pump Module C-605, fast separation with reversed phase and separations can be performed with sample sizes up to 100 g. Ideal for use with glass and plunger columns and silica gel particle sizes < 40 μm.

Pump Manager C-615
The Pump Manager C-615 with two Pump Modules C-601/C-605 for binary solvent gradients. The efficient solvent mixing under pressure and the pulsation free solvent flow eliminate vapour bubbles and result in maximum separation performance.

Vacuum Pump/peristaltic Pump
Transfer Solvent From Mobile phase Reservoir to Flash Pump.

Sample Injection Systems
Injection systems are designed to facilitate column loading with liquids and low solubility oils and solids. Regardless of the nature or quantity of the material.

Injection Valve
For the sample injection of 0–5 ml.

Elute Glass Column
Prep Elute Glass Column for use in combination with the Injection Unit for loading dry or barely soluble samples up to either 18 ml or 53 ml. Pressure Range of up to 50 bar or 40 bar.

Sample Chamber 100 ml
Sample Chamber 100 ml for use in combination with the Injection Unit for loading sample volumes of 10 to 100 ml including N2 gas valve (on/off). Glass parts with larger volumes 250 ml, 500 ml and 1000 ml on demand.

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